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2
nd
CAT PORT
Beginning with version 7.0, Router provides unique control capability: the 2
nd
CAT Port is an intelligent data
fork (software 'Y' connector) that allows a second application to share control of the radio. Router monitors
when data is sent from each application and routes the radio's responses to the correct virtual port.
IMPORTANT: Both applications must use same communication parameters (baud rate, data length, parity
and number of stop bits) for proper operation!
Neither CAT port has priority. Polls/commands from the application are processed alternately. In order to
avoid collisions and confusion due to unexpected data, responses from the radio are returned only to the
application that generated the command. Unsolicited data such as automatic frequency/mode updates
(Icom "transceive" packets or "Auto-information" data from Kenwood, Elecraft and recent Yaesu
transceivers) is forwarded to both CAT ports.
Due to physical limitation of data channel throughput and the controller capabilities in various transceivers,
there are several important rules which must be observed.
●
Combined data from both applications must not exceed maximum throughput of the radio control
port and transceiver controller. In other words, the polling rate from one application may need to be
decreased to provide data space for the second application and vice versa.
●
Applications must be tolerant of delayed responses from the radio. Each application must wait for
the radio to respond when the another application is communicating with the radio.
●
Due to protocol deficiencies in handling VFO split commands with many transceivers (particularly
Icom), split mode must be initiated and ended by only one application and manual split control
(from the front panel of the radio) should not be used.
NOTE: Despite extensive testing using various combinations of applications for the CAT and 2
nd
CAT ports, microHAM cannot guarantee proper operation with every potential combination of
applications.
FSK & 2
nd
FSK PORTS
The FSK channel is used by the application program to send the FSK keying signal. FSK is used primarily
for RTTY. It is very important to understand the difference between FSK and AFSK.
FSK is a digital (On/Off) signal from the computer serial port (or an external modem). This signal is used in
the transceiver to generate a frequency shift. FSK must be supported by the transceiver (this mode is
commonly labeled RTTY or FSK).
AFSK is a analog (audio) signal generated by the computer sound card (or external modem) used in the
transceiver modulation circuits for operating digital modes as RTTY, PSK31, AMTOR etc. Computer sound
card generated AFSK or PSK does not require special transceiver support and can be used in the LSB,
USB or FM mode of the transceiver. Some radios have dedicated modes for AFSK (generally labeled PKT
or DATA) with special features.
It is very important to properly adjust the audio drive level of an AFSK system so as to not overdrive
the first transmit audio amplifier stage in the transceiver and produce a wide, distorted signal, full of
intermodulation products. It is important to appreciate that distortion generated at this point due to
overdrive CANNOT be reduced or eliminated by the reduction of the microphone gain control – it is
the signal level that must be adjusted to be about the same as would be expected from a
microphone. The microphone gain control then becomes a form of transmit power control.
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